NLO for Higgs signals

Transcription

1 NLO for Higgs signals Gudrun Heinrich Max Planck Institute for Physics, Munich

2 P.Meridiani, EPS 2017

3 P.Meridiani, EPS 2017 we need to be sure about the systematic uncertainties to see something like this

4 status of higher (fixed) order predictions involving H (see also Kirill s talk) gg! H tot d bonus N^3LO NNLO N^3LL threshold resum. NLO EW, mixed QCD/EW VBF N^3LO NNLO NLO EW WH/ZH t th NNLO NNLO NLO EW gg to ZH mt dep. approx. NLO NLO NNLL threshold resum. NLO EW H + single top NLO NLO H +jets HH black: m t!1 1j: NNLO 1j: NNLO NNLO NNLO NLO (HEFT) blue: m q dependence NLO up to 3jets H+1jet NLO: mb dependence NNLL resum. NLL resum.

5 status of higher (fixed) order predictions involving H gg! H VBF WH/ZH t th H + single top H +jets HH tot d bonus N^3LO Anastasiou et al N^3LO Bolzoni, Maltoni, Moch, Zaro 10; Dreyer, Karlberg 16 NNLO (+NNLL) NNLO NNLO NNLO NLO EW Brein, Djouadi, Harlander 03; Brein, Harlander, Wiesemann, Zirke 11 NLO NLO NLO Beenakker et al 01; Dawson, Reina 02; Frederix et al 14 NLO 1j: NNLO 1j: NNLO Boughezal, Caola et al 15; Boughezal et al 15; Chen et al 15; Dulat, Mistlberger 17 NNLO De Florian, Mazzitelli 15; Steinhauser et al 15 NNLO N^3LL threshold resum. Bizon, Monni, Re, Rottoli, Torrielli 17 De Florian, Grazzini, Tommasini 11, 12 NLO EW, mixed QCD/EW Dulat, Mistlberger 17 Degrassi, Maltoni 04; Actis, Passarino, Sturm, Uccirati 08; Anastasiou et al 08 Cacciari, Dreyer, Karlberg, Salam, Zanderighi 15 Ferrera, Grazzini, Tramontano 11, 14 Demartin, Maltoni, Mawatari, Zaro 15 De Florian et al 16 NLO EW Ciccolini, Denner, Dittmaier 07 Denner, Dittmaier, Kallweit, Mück 12 gg to ZH 1/mt Altenkamp et al 12 NNLL threshold resum. Harlander et al 14 NLO EW Frixione et al 14; (on-shell) Denner, Lang, Pellen, Uccirati 16 NNLL threshold resum. Kulesza et al 15 NLO up to 3jets Cullen et al 13 H+1jet NLO: mb dependence Lindert, Melnikov, Tancredi, Wever 17 NLO Borowka, Greiner, GH, Jones, Kerner, Schlenk, Schubert, Zirke 16 NLL resum. Ferrera, Pires 16

6 status of parton shower matched results gg! H VBF NNLO NLO Hamilton, Nason, Re, Zanderighi 13; Höche, Li, Prestel 14; Alioli et al 13, 15 Nason, Oleari 10; Frixione, Torrielli, Zaro 13; Campanario et al 13; Jäger et al 14 WH/ZH NLO (+ 0/1-jet merging) Luisoni, Nason, Oleari, Tramontano 13 NNLO Goncalves, Krauss, Kuttimalai, Maierhöfer 15; Astill, Bizon, Re, Zanderighi 16 NLO QCD+EW Granata, Lindert, Oleari, Pozzorini 17 t th H + single top NLO NLO Frederix et al 11; Garzelli et al 11; Hartanto et al 15; QCD and EW: Denner, Lang, Pellen, Uccirati 16 Demartin, Maltoni, Mawatari, Zaro 15 H +jets NLO up to 2jets Buschmann, Goncalves, Krauss, Kuttimalai, Schönherr, Plehn 14 Frederix, Frixione, Vryonidou, Wiesemann 16 HH NLO GH, Jones, Kerner, Luisoni, Vryonidou 17; Jones, Kuttimalai 17

7 some pressing problems to solve at NLO: quark mass effects boosted Higgs can resolve loops from heavy BSM particles and heavy SM particles (top)! EW corrections, combination QCD/EW consistent combination of EFT and SM NLO corrections finding optimal scales/assessment of scale uncertainties (also shower/resummation scale uncertainties) multi-jet merging improve logarithmic accuracy of parton showers

8 Higgs pt high-energy resummation of Higgs pt in gg! H with off-shell gluons Marzani, Ball, del Duca, Forte, Vicini 08; Forte, Muselli 15; Caola, Forte, Marzani, Muselli, Vita 16 for p T,h!1 : d /dp 2 T,h! p 2 T,h 1 d /dp 2 T,h! p 2 T,h 2 Caola, Forte, Marzani, Muselli, Vita 16

9 quark mass effects in Higgs + jets Greiner, Höche, Luisoni, Schönherr, Winter 16 cross sections (+Ntuples) for H+1,2,3 jets calculated at NLO in HEFT ( m t!1 limit ) LO with full m t,m b dependence default scale choice: basic cuts:

10 quark mass effects in Higgs + jets m t!1 limit starts to fail at p T,H 200 GeV different jet multiplicities show very similar behaviour leading jet pt distribution also similar suggests that resolution of top quark loops is driven by pt,h or largest pt in the event jet multiplicity seems to play minor role needs further investigation (backup slide)

11 Effect of VBF cuts VBF cuts can enhance the deviations of HEFT to full theory

12 bottom quark effects well below the scale uncertainties even at low pt depend on jet multiplicity destructive interference between top- and bottom-quark loops for H+1jet

13 Higgs+0,1,2 jets + parton shower H + n jets: Frederix, Frixione, Vryonidou, Wiesemann 16 exact mass dependence in real radiation exact 2-loop virtual for n=0 rescaled HEFT virtual for n=1,2 see also Buschmann, Goncalves, Krauss, Kuttimalai, Schönherr, Plehn 14

14 Higgs + jet Lindert, Melnikov, Tancredi, Wever 17 Chris Wever, RadCor 2017

15 Higgs + jet Lindert, Melnikov, Tancredi, Wever 17 large relative corrections top-bottom interference to top-top large mb renormalisation ambiguities (light bands) reduced at NLO, in particular at low pt

16 Higgs + jet Neumann, Williams 17 exact mass dependence in real radiation virtual part: on amplitude level NLO*: 1/m t expansion fullasy: expansion on amplitude squared level method works well for scales up to about 300 GeV

17 towards Higgs + jet at full NLO Jones, Kerner, Luisoni

18 Higgs boson pair production Frederix, Frixione, Hirschi, Maltoni, Mattelaer, Torrielli, Vryonidou, Zaro 14 largest cross section from gluon fusion, but still gghh 10 3 ggh

19 Higgs boson pair production in gluon fusion LO with full heavy quark mass dependence Glover, van der Bij 88, Plehn, Spira, Zerwas 96 m t!1limit: Higgs Effective Field Theory (HEFT) Note: o p HEFT strictly valid only for ŝ 2m HH production threshold: 2m H < p t ŝ ) validity of HEFT limited to 250 GeV < p ŝ<340 GeV

20 Higgs boson pair production in gluon fusion LO with full heavy quark mass dependence Glover, van der Bij 88, Plehn, Spira, Zerwas 96 m t!1limit: Higgs Effective Field Theory (HEFT) Note: o p HEFT strictly valid only for ŝ 2m HH production threshold: 2m H < p t ŝ ) validity of HEFT limited to 250 GeV < p ŝ<340 GeV Born-improved NLO HEFT : rescale by M LO (m t )/M LO HEFT NLO in Born-improved HEFT Dawson, Dittmaier, Spira 98 (HPAIR) K ' 2 supplemented with 1/m t expansion: (±10%) Grigo, Hoff, Melnikov, Steinhauser 13, 15 ; Degrassi, Giardino, Gröber 16 full mass dependence in NLO real radiation ( FTapprox ) -10% Frederix, Hirschi, Mattelaer, Maltoni, Torrielli, Vryonidou, Zaro 14; Maltoni, Vryonidou, Zaro 14

21 Higgs boson pair production in gluon fusion NNLO in m t!1 limit: +20% total xs NNLO De Florian, Mazzitelli 13 including all matching coefficients Grigo, Melnikov, Steinhauser 14 supplemented with 1/m t expansion: Grigo, Hoff, Steinhauser 15 soft gluon resummation NNLL Shao, Li, Li, Wang 13; De Florian, Mazzitelli 15 +9% differential NNLO De Florian, Grazzini, Hanga, Kallweit, Lindert, Maierhöfer, Mazzitelli, Rathlev 16

22 Higgs boson pair production in gluon fusion NNLO in m t!1 limit: +20% total xs NNLO De Florian, Mazzitelli 13 including all matching coefficients Grigo, Melnikov, Steinhauser 14 supplemented with 1/m t expansion: Grigo, Hoff, Steinhauser 15 soft gluon resummation NNLL Shao, Li, Li, Wang 13; De Florian, Mazzitelli 15 +9% differential NNLO De Florian, Grazzini, Hanga, Kallweit, Lindert, Maierhöfer, Mazzitelli, Rathlev 16 NLO calculation with full top mass dependence Borowka, Greiner, GH, Jones, Kerner, Schlenk, Schubert, Zirke 16 4 independent scales s12, s23, mh, mt all integrals calculated numerically with g t H SecDec g H Borowka, GH, Jones, Kerner, Schlenk, Zirke 15 Borowka, GH, Jahn, Jones, Kerner, Schlenk, Zirke 17 q T resummation NLL+NLO Ferrera, Pires 16 graphics by S.Jones

23 numerical evaluation of multi-loop integrals algorithm: T. Binoth, GH 00 version 1.0: J. Carter, GH 10 version 2.0: S.Borowka, J. Carter, GH 12 version 3.0: pysecdec: S.Borowka, GH, S.Jones, M.Kerner, J.Schlenk, T.Zirke 15 S.Borowka, GH, S.Jahn, S.Jones, M.Kerner, J.Schlenk, T.Zirke 17

24 numerical evaluation of multi-loop integrals algorithm: T. Binoth, GH 00 version 1.0: J. Carter, GH 10 version 2.0: S.Borowka, J. Carter, GH 12 version 3.0: pysecdec: S.Borowka, GH, S.Jones, M.Kerner, J.Schlenk, T.Zirke 15 S.Borowka, GH, S.Jahn, S.Jones, M.Kerner, J.Schlenk, T.Zirke 17 New! can be used as an integral library

25 calculation: building blocks amplitude generation with 2 setups (custom made and GoSam-2loop ) amplitude reduction with Reduze [C. Studerus, A. v.manteuffel] non-planar integrals computed mostly without reduction integrals calculated numerically with SecDec g t H total number of integrals: before reduction: ~10000, after reduction ~330, after sector decomposition (3086 non-planar) used finite basis for planar integrals g H real radiation: (a) GoSam-1L + Catani-Seymour dipole subtraction (b) GoSam-1L + POWHEG

26 top mass effects total cross sections at 14 TeV HXSWG:

27 top mass effects: energy dependence scale uncertainties preliminary, ± 0.3 stat. uncertainty relative difference Born-improved NLO HEFT to full NLO: 14 TeV: 16.4% 27 TeV: 21.2% 100 TeV: 31.5%

28 Higgs boson pair invariant mass d /d mhh [fb/gev] TeV LO TeV B-i. NLO HEFT NLO FTapprox LO basic HEFT NLO basic HEFT NLO d /d mhh [fb/gev] LO B-i. NLO HEFT NLO FTapprox LO basic HEFT NLO basic HEFT NLO K factor m hh [GeV] K factor m hh [GeV] for large invariant masses: Born-improved NLO HEFT overestimates by about 50%, FTapprox by about 40% (at 14 TeV, worse at 100 TeV) top quark loops resolved HEFT has wrong scaling behaviour at high energies

29 rapidity of the Higgs boson pair 14 TeV 100 TeV

30 d NLO NLO-improved NNLO HEFT NNLO HEFT: De Florian, Grazzini, Hanga, Kallweit, Lindert, Maierhöfer, Mazzitelli, Rathlev NLO-improved NNLO HEFT : [Borowka, Greiner, GH, Jones, Kerner, Schlenk, Zirke ] i.nnlo HEFT dm hh = d NLO dm hh d NNLO HEFT/dm hh d HEFT/dm hh NLO bin-by-bin rescaling at observable level by NNLO HEFT K-factor d /d mhh [fb/gev] LO NLO NLO-i. NNLO HEFT would lead to 0 = fb K factor m hh [GeV]

31 variation of triple Higgs coupling = cross section has a minimum around 160 LO NLO NLO HEFT NLO FTapprox [fb] 100 BSM / SM = 2 due to destructive interference between diagrams containing and box-type diagrams LO B-i. NLO HEFT NLO FTapprox LO basic HEFT NLO basic HEFT NLO d /d mhh [fb/gev] = degeneracy due to quadratic mhh [GeV] dependence 1.2 LO B-i. NLO HEFT NLO FTapprox LO basic HEFT NLO basic HEFT NLO =0 K factor K factor 0.1 d /d mhh [fb/gev] d /d mhh [fb/gev] 1 K factor mhh [GeV] distributions can discriminate between degenerate 1.0 = LO B-i. NLO HEFT NLO FTapprox LO basic HEFT NLO basic HEFT NLO values mhh [GeV]

32 variation of triple Higgs coupling

33 combination with parton showers GH, S.Jones, M.Kerner, G.Luisoni, E.Vryonidou 17 avoid evaluation of two-loop amplitude for each phase space point two-loop amplitude depends only on ŝ, ˆt (m t,m H fixed) construct 2-dim grid variable transformation to achieve more uniform distribution (ŝ) = q 1 4m 2 H /ŝ combination with POWHEG and MadGraph5_aMC@NLO POWHEG-BOX-V2: User-Process-V2/ggHH and Sherpa

34 combination with parton showers GH, S.Jones, M.Kerner, G.Luisoni, E.Vryonidou 17 avoid evaluation of two-loop amplitude for each phase space point two-loop amplitude depends only on ŝ, ˆt (m t,m H fixed) construct 2-dim grid variable transformation to achieve more uniform distribution (ŝ) = q 1 4m 2 H /ŝ combination with POWHEG and MadGraph5_aMC@NLO POWHEG-BOX-V2: User-Process-V2/ggHH and Sherpa New! see Silvan Kuttimalai s talk

35 grid validation slide: S.Jones

36 dependence on shower parameters hdamp=h limits amount of exponentiated hard radiation hdamp = 1

37 dependence on shower parameters hdamp=h limits amount of exponentiated hard radiation hdamp = 1 shower effects large but order(s) of magnitude smaller than difference to Born-improved HEFT

38 NLO is not a solved problem finite mass effects are important in particular in tails of distributions, where they need to be distinguished from BSM effects summary & outlook NLO with full top mass dependence for pp! HH,pp! H + jet,gg! HZ means 2-loop integrals with many kinematic scales (too many for an analytic solution currently?) lots of progress recently HH@NLO done numerically (SecDec) combination of QCD corrections with NLO EW and EFT talk of Alexander Mück increase precision by improvements on parton shower side (matching uncertainties, merging, log. acc.) and resummation many talks talk of Pier-Francesco Monni

39 BACKUP SLIDES

40 compare POWHEG and old Qsh old shower starting scale Qsh: picked with some probability distribution in version 2.5.3: new Qsh picked with some probability distribution in new Qsh

41 compare POWHEG and new default Qsh matches onto NLO fixed order at large pt

42 compare Pythia6 and Pythia8

43 ratio to lower jet multiplicity shows similar behaviour quark mass effects in Higgs + jets

44 quark mass effects in Higgs + jets Gionata Luisoni, DIS 2017

45 quark mass effects in Higgs + jets Gionata Luisoni, DIS 2017 LO H+3 ( 10) LO H+3 (veto) d /dpt, H [pb/gev] LO H+3 mt,b ( 10) LO H+3 mt,b (veto) 101 LO H+3 mt ( 10) LO H+3 mt (veto) 100 GoSam + Sherpa pp! H + 3 jets at 13 TeV CT14nlo, R = 0.4 anti-kt, jet < 4.4, pt,jet = 100 GeV d /dpt, j1 [pb/gev] 101 preliminary LO H+3 mt,b ( 10) LO H+3 mt,b (veto) LO H+3 ( 10) LO H+3 (veto) GoSam + Sherpa pp! H + 3 jets at 13 TeV CT14nlo, R = 0.4 anti-kt, jet < 4.4, pt,jet = 100 GeV preliminary no veto applied 10 Ratio wrt. LO using mt! 1 approximation. X / LO H+2 X / LO H+2 Ratio wrt. LO using mt! 1 approximation no veto applied 10 1 pt, H < 100 GeV Ratio wrt. LO using mt! 1 approximation. X / LO H+2 (veto) X / LO H+2 (veto) Ratio wrt. LO using mt! 1 approximation Higgs boson transverse momentum: pt, H [GeV] 1000 LO H+3 mt ( 10) LO H+3 mt (veto) 100 pt, H < 100 GeV Leading-jet transverse momentum: pt, j1 [GeV] 1000

46 Caola, Forte, Marzani, Muselli, Vita 16 Higgs pt high-energy resummation of Higgs pt in gg! H with off-shell gluons

47 Higgs + jet Neumann, Williams 17